A trowel is a simple hand tool used to layer or “slot in” mortar between stones or bricks by a mason. While the spelling has changed, “drop trow” is long forgotten slang from the masonry trade meaning to immediately “drop the trowel”, stop working, and/or walk away from the job. The term was often used in reference to unionization and labor strikes in the 1880’s through the 1950’s in the United States.